In accordance with development of near field communication technology, recently released portable devices provide a function of performing data transmission and reception using near field communication. Accordingly, an antenna module for near field communication and an antenna module for electronic payment are mounted in the portable device. As the antenna module used for near field communication, a near field communication (NFC) antenna module is used. The NFC antenna module is a non-contact type near field wireless communication module using a frequency band of about 13.56 MHz as one of electronic tags (RFID) and transmits data between devices at a distance of about 10 cm. The NFC is extensively used for transmission of product information in a supermarket or a general market or travel information for visitors, traffic, admission control locking device, or the like, in addition to payment.
Further, as recently released portable devices require a function relating to electronic payment using a portable device such as Apple pay, Samsung Pay, or the like, an antenna for electronic payment is mounted. For example, since Samsung Pay performs electronic payment using a magnetic secure transmission scheme, in a portable device supporting Samsung Pay, a magnetic secure transmission (MST) antenna is mounted.
Further, application of a cover made of a metal material (hereinafter, referred to as metal cover) to the recently released portable devices is on a rising trend. If a back cover 10 of a portable device is made of a metal material as illustrated in FIG. 1, performance of an antenna module 20 (that is, an NFC antenna module and MST antenna module) connected to a circuit board 30 of the portable device is difficult to be implemented. That is, if the back cover 10 of the portable device is made of a metal material, since current flows in the back cover 10 in an opposite direction to the antenna module 20 to perform a shielding function of attenuating a signal of the antenna module 20, formation of a radiation field is blocked, such that an antenna performance may not be implemented.
Thus, various researches for implementing performance of an antenna module mounted in a portable device have been conducted. For example, as illustrated in FIG. 2, according to the related art, in a portable device 40 using a back cover 10 made of a metal material, a slit 50 or an opening (not illustrated) is formed in the metal cover to implement performance of the antenna module 20, and an antenna module 20 is mounted so as to partially overlap the slit 50 or the opening. Accordingly, the performance of the antenna module 20 can be implemented through coupling effect between the antenna module 20 and the back cover 10 at the slit 50 or the opening.
However, if the slit 50 or the opening is formed to implement performance of the antenna module 20, a manufacturing process of the portable device 40 becomes complicated, such that manufacturing costs are increased, and the slit 50 or the opening needs to be reflected to an appearance design.
Meanwhile, as illustrated in FIG. 3, as user environment has become diverse recently, the portable device 40 requires a structure capable of performing near field communication and electronic payment in a plane direction (i.e. a back surface of the portable device) and a vertical direction (i.e. a side surface of the portable device).
However, as illustrated in FIG. 4, since a radiation pattern 24 is formed in the existing antenna module 20 (that is, NFC antenna module and MST antenna module) by winding a coil on an upper surface of a shielding sheet 22, it is difficult to implement the antenna performance in the vertical direction (i.e. a side surface direction of the portable device).